class Phone:
    __current_voltage = 0.5

    def __keep_single_core(self):
        print("CPU以单核模式进行")

    def call_by_5g(self):
        if self.__current_voltage > 1:
            print("5g通话以开启")
        else:
            self.__keep_single_core()
            print("电量不足不能开启5g通话，并已设置单核运行")


phone = Phone()
phone.call_by_5g()
